Eyeglasses



April 11, 1933.- K, MARTI 1,903,593

EYEGLASSES Fi led Nov. 27, 1928 Patentecl Apr. .11, 1933 UNITED STATES mm mm, or na'rizmwow; exam! I mamas Application filed 1mm; 2?, 1m, Serial No. 322,259, and in Germany Inch a4, 1928. y

The present invention relates to improved bifocal eyeglasses that are composed of a distance portion and a reading portion the tical axes of which two portions coincide. he

5 improved construction allows of the eyeglasses of this ty to be easily produced by wholesale manuf sihture with an absolutely uniform result and consists in the fact that the distance portion is formed by one sole 1 blank and that both said portions are united with one another by welding or fusing. In manufacturing my improved eyeglasses I I proceed as follows:

The reading portion is constituted by a prepared glass body having something of the shape of part worked on the places to be welded, whilst the distance portion consists of one sole piece the material of which has a lower softening or melting point than that of the reading portion. when softened by heating is enabled to lower towards the reading portion and can be pressed on it, whereupon the whole system in 5 known manner is ground to finished state. Owing to the fact'that I give to the, nearly semicircular additional lens which forms the reading portion the same optical axis as to the distance portion, the whole system is cen- 0 tered, so that no image jump can occur when the eye passes from the upper distance portion to the reading portion. I further. attain by the described method of manufacture the advantage that no air or glass bubbles can remain between the two surfaces to be welded together, the presence of which bubbles would render useless the e eglass.

The two sorts of g ass the described bifocal eyeglass is made of, advantageously are so 4 chosen in a well known manner that the combination is free from disturbing colored margins, that means, is achromatic.

In order to allow of myinvention to be more easily understood, the specification is accompanied by a drawing in which of a lens which is optically- Consequently, the distance portion Figure 1 shows the finished bifocal glass in section,

Figure 2 is a section through the pressing die with the two glass portions in place, while Figure 3 shows the rough system previous to being ground.

As to be seen fromFig-ure 2, I use a die or. base plate n in a corresponding recess of which the reading portion a is embedded while the. distance portion 7 is put thereon. When heated in a suitable furnace the distance portion lowers owing to its lower softv ening point, so that the reading portion 'n penetrates therein with its prepared faces a, b, to which end a slight pressure may be applied still on portion f. After the pressing operation the two glass portions possess the rough. shape to be seen from Figure 3, and the system is thenfinished by grinding. I

It may be noted'that the connecting' sur- 55 faces of the two glass portions need not to be spherical ones under all circumstances, in the contrary, it will be convenient in certain cases to prefer aspherical connecting surfaces the curvature of which flattens toward the edge of the eyeglass. This results in the advantage of the passage from the reading portion to the distance portion becoming milder, this being taken very agreeably in particular in going upstairs or downstairs.

What I claim and desire to secure by Letters Patent, is i The process for the manufacture of a multiple focus lens consisting of a distance portion and a readin portion formed of a me so tional part of a ens having a sphericallyshaped surface and a plane lateral'surface, which comprises preparing only the spherically-shaped and lateral surfaces of said reading portion, formed of a fractional part of a lens, which are designed to be joined to the distance portion, heating the non-recessed distance portion to a'point above the softening point thereof and below the softenmg point of said reading portion, superim- 00 posing the spherically-she, d surface of said reading portion with said istance portion in its heated condition, joining said distance portion of the spherically-shaped and lateral surfaces of said reading portion by apply-. ing a pressure to the former in addition to normally existing pressures without afl'ec t-o ing the prepared surfaces upon said reading portion, and finishing the composite lens thus formed.

Tntestimony whereof I aflix m signature.

' KARL RTIN. 

